The syringe of the invention is generally similar to the syringe described in U.S. Pat. No. 4,108,178 which issued Aug. 22, 1978 in the name of the present inventor and which is assigned to the present assignee.
As described in the patent, the usual syringes available prior to the subject matter of the patent include pushbutton valves to control the flow of streams of compressed air and water to a nozzle which is mounted on one end of the instrument, the valves being sealed by O-rings. Apart from being complex and expensive, the prior art syringes have a tendency to stick due to debris in the controlled fluids. The syringe described in the patent uses pinch valves, and it is rugged in its construction, simple in its operation, inexpensive and uncomplicated, and it has no tendency to stick, even when subjected to rough usage. Additionally, the tubes may periodically be shifted to new pinch points to prolong tube life.
As mentioned above, the syringe of the present invention, like the syringe disclosed in the patent, is a pinch valve type of syringe, and it exhibits all the advantages of the syringe disclosed in the patent. In addition, the syringe of the present invention is simpler in its construction than the syringe disclosed in the patent, and is sturdier and more reliable. Moreover, the syringe of the invention incorporates certain features which are not found in the syringe of the patent, and which will be described in the following specification.
The syringe of the present invention, as mentioned above, may be used to control a wide variety of liquids, gases, and particulate matter, and it has a wide range of utility apart from dental work, for variably and proportionately metering and dispensing a multiplicity of different liquids.